The present invention relates generally to electrical devices. More specifically, the present invention relates to methods of manufacturing devices having circuit protection.
Printed circuit (PC) boards have found increasing application in electrical and electronic equipment of all kinds. For example, an onslaught of wireless communications has created the need for large quantities of low cost, high performance circuit boards. In addition to increasing the performance of such devices, manufacturers strive to reduce the physical size of the devices.
Of course, given the sensitive nature of such devices, it is necessary to protect these printed circuit boards against electrical overloads and overvoltage. This protection may be provided by temperature, voltage or current protection components that are physically secured to the PC board. For example, such protection can be provided by positive temperature coefficient (PTC) elements, electrostatic discharge surface-mounted devices (ESD/SMD), and subminiature fuses.
PC boards often incorporate bores, through-holes, slots or apertures within the substrate of the PC board. Traditionally, a drilling process is used to create the apertures. Drilling processes can be used to create through-holes, holes that extend all the way through a device, or blind holes. A blind hole is an aperture that extends from a surface to a layer thereunder. Blind holes do not extend through the device. Heretofore, such blind holes could only be created through the use of a drilling process.
However, drilling processes typically generate a resin smear on the substrate. This resin smear can cover the surface of the conductive inner layers and prevent good electrical connection. Expensive and environmentally harsh chemical processes typically must be used to remove the resin smear.
Thus, there is a need for new processes and methods for producing through-holes and other apertures in substrates, such as printed circuit boards, flexible circuits and the like.